• Title/Summary/Keyword: Mold/Casting Interface

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Experimental Research of Piece-Mold Casting: Gilt-Bronze Pensive Bodhisattva

  • Yun, Yong-Hyun;Cho, Nam-Chul;Doh, Jung-Mann
    • Journal of Conservation Science
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    • v.37 no.4
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    • pp.340-356
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    • 2021
  • We have tried the experimental research of lost-wax casting to reconstruct Gilt-Bronze Pensive Bodhisattva; preliminary and reconstruction experiment based on ancient texts. Main object to reconstruct is Korean National Treasure No.83, Gilt-Bronze Pensive Bodhisattva (Maitreya), then we measure alloy ratio and casting method based on the scientific analysis. Other impurities were removed from the base metal components(copper : tin : lead) and their ratio was set to 95.5 : 6.5 : 3 where the ratios for tin and lead were increased by 2.5% each. The piece-mold casting method was used, and piece-mold casting experiments were carried out twice in this study but supplementary research on piece-mold casting was necessary. The microstructure was confirmed to be typical cast microstructure and the component analysis result was similar to that of the prior study. Analysis of the chemical composition is confirmed to copper, tin, lead, and zinc, and the chemical composition of the matrix was 87.8%Cu-7.5%Sn-2.7%Pb-2.1%Zn, and similar to previous experimental research. Also resulted in the detection of small impurity in Zn. Analysis of the mould revealed that the mould was fabricated by adding quartz and organic matter for structural stability, fire resistance, and air permeability. We expect that our research will contribute to provide base data for advanced researches in future.

Effects of Superheat and Coating Layer on Interfacial Heat Transfer Coefficient between Copper Mold and Aluminum Melt during Solidification (응고중 구리 주형과 알루미늄 용탕의 계면열전달계수에 미치는 용탕과열도와 도형재의 영향)

  • Kim, Hee-Soo;Shin, Je-Sik;Lee, Sang-Mok;Moon, Byung-Moon
    • Journal of Korea Foundry Society
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    • v.24 no.5
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    • pp.281-289
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    • 2004
  • The present study focused on the estimation of the interfacial heat transfer coefficient as a function of the surface temperature of the aluminum casting at the mold/casting interface to investigate the effects of superheat and coating layer. The casting experiments of aluminum into a cylindrical copper mold were systematically conducted to obtain the thermal history during solidification. The thermal history recorded by four thermocouples embedded both in the mold and the casting was used to solve the inverse heat conduction problem using Beck's method. The effects of superheat and coating on the interfacial heat transfer coefficient in the liquid state, during the solidification, and in the solid state were comparatively discussed. In the liquid state, the interfacial heat transfer coefficient is thought to be affected by the roughness of the mold, the wettability of the casting on the mold surface, and the thermophysical properties of the coating layer. When the solidification begins, the air gap forms between the casting and the mold, and the interfacial heat transfer coefficient becomes a function of the air gap as well as surface roughness and the superheat. In the solid phase, it depends only upon the thermal conductivity and the thickness of the air gap. The coating layer reduces seriously the interfacial heat transfer coefficient in the liquid state and during the solidification.

Finite Element Analysis of Solidification Processes of Axisymmetric Castings Considering Phase Change and Contact (상변화와 접촉을 고려한 축대칭 주조 응고공정의 유한요소 해석)

  • Ghoo, B.Y.;Keum, Y.T.;Lee, J.K.
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.1
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    • pp.126-141
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    • 1997
  • The purpose of this research is to develope a FEM program for analyzing solidification processes of axisymmetric casting, considering phase changes and the contact between the metal and mold. Tempera- ture recovery method is employed fro considering the phase changes releasing the latent heat and the coin- cident node method is used for calculating the amount of heat transfer between the metal and mold. Tan- gent modulus algorithm is adopted for calculating flow stress and a gap element is employed for modeling the interface between the mold and metal in finding deformed shapes. In order to verify the developed program, axisymmetric aluminum and steel casting processes are simulated. Temperature distribution, phase front position, and shrinkage and porosity creation are compared with measurements, FIDAP results, and good agreements are examined.

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The Effects of Pattern Coatings on the Solidification of Pure Aluminum Castings and the Thermal Behavior of Molds in FMC Processes (FMC법에서 모형 도형제가 순알루미늄 주물의 응고와 주형의 열적거동에 미치는 영향)

  • Cho, N.D.;Kim, Y.N.
    • Journal of Korea Foundry Society
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    • v.7 no.2
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    • pp.122-132
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    • 1987
  • Full mold casting process is a new technique offering numerous advantages and promising possibilities. The present study is aimed to bring out the results of experiments carried out to study the effect of pattern coatings on the solidification of 99.5% pure aluminum plate-shaped castings in the various sand molds and the thermal behavior of the molds. The results of the investigation indicate that (i) with increase in pattern coating thickness, the relative chilling power decreases gradually for silica and increases for zircon coating, and (ii) the application of a pattern coating significantly reduces the maximum interface temperature by the mold which is more pronounced in the case of thinner mold wall. The investigation also indicates that Chvorinov's rule is not found to be valid for the casting in the full mold, with or without pattern coating. Therefore in full mold process, the pattern coating thickness will be a very important parameter in the study of thermal behavior.

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Effect of the Degree of Cold Working on the Microstructures for TiNi/6061Al Composites by Permanent mold Casting (금형주조법에 의한 TiNi/6061Al 복합재료의 미세조직에 미치는 냉간가공도의 영향)

  • Park, Seong-Gi;Sin, Sun-Gi;Park, Gwang-Hun;Seong, Jang-Hyeon;Park, Yeong-Cheol;Lee, Gyu-Chang;Lee, Jun-Hui
    • Korean Journal of Materials Research
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    • v.11 no.12
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    • pp.1028-1034
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    • 2001
  • The 2.5 vol% TiNi/6061Al composites were fabricated by permanent mold casting. The microstructures and tensile test for the cold rolled composites with maximum 50% reduction ratio were investigated. In the case of TiNi fiber with 2mm interval in preform, the interface bonding of fabricated composites were good, interface diffusion layer of this composites was made by the mutual diffusion. Transverse section of TiNi fiber was decreased with increasing reduction ratio and longitudinal section of TiNi fiber showed multiple wave phenomenon. And the tensile strength of composites at 38% reduction ratio was the most high. In the case of over 38% reduction ratio, the decrease of the tensile strength was due to TiNi fiber rupture by excess working. The fracture mode was appeared brittle fracture with increasing reduction ratio.

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A Study on the Solidification Structure of Al-Si Alloy by the Continuous Casting with the Heated Mold (가열주형식 연속주조법에 의한 Al-Si합금의 응고조직에 관한 연구)

  • Kim, Won-Tae;Moon, Jeong-Tak;Kim, Myung-Han;Jo, Hyung-Ho
    • Journal of Korea Foundry Society
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    • v.14 no.5
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    • pp.464-470
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    • 1994
  • The horizontal continuous casting method with the heated mold was applied to study the solidification structures of the pure Al and Al-0.5wt%Si and Al-1.0wt%Si alloy rods. The results could be summarized as follows: 1. The S/L interface structures of pure Al represented the hexagonal cells at the casting speed of 590 and 350mm/min, respectively. However, the hexagonal cells became irregular as the casting speed and(or) Si amount increased. 2. The striation increased as the Si amount and casting speed increased and was found to result from the occurrence of growth twin crystals by XRD analysis. 3. The striation did not affect the mechanical and electrical property of the drawn wire from the casted rod. This means the striation is not a serious defect which has to consider in the production of micro-sized fine wire in the drawing process.

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Effect of cold rolling on the microstructures of TiNi/6061Al smart composites. (TiNi/6061Al 지적 복합재료의 미세조직에 미치는 냉간압연의 영향.)

  • 박성기;신순기;이준희
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2002.10a
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    • pp.127-130
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    • 2002
  • The 2.5 vol% TiNi/6061Al composites were fabricated by permanent mold casting, and its microstructures and tensile test for the cold rolled composites with maximum 50% reduction ratio were investigated. In the case of TiNi fiber with 2mm interval in preform, the interface bonding of fabricated composites were good. EPMA analysis results were found the small amount of Mg, Si segregated interface of diffusion layer. Transverse section of TiNi fiber was decreased with increasing reduction ratio and 40% reduction ratio was observed microcrack from TiNi fiber. And the tensile strength of composites at 38% reduction ratio was 194MPa. In the case of over 38% reduction ratio, the decrease of the tensile strength was due to TiNi fiber rupture by excess working. The fracture mode was appeared brittle fracture with increasing reduction ratio

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NUMERICAL METHOD FOR MOLTEN METAL FLOW SIMULATION WITH CUT CELL (Cut Cell을 고려하는 주조유동 해석 방법)

  • Choi, Y.S.;Hong, J.H.;Hwang, H.Y.
    • 한국전산유체공학회:학술대회논문집
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    • 2011.05a
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    • pp.518-522
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    • 2011
  • Cartesian grid system has mainly been used in the casting simulation even though it does not nicely represent sloped and curved surfaces. These distorted boundaries cause several problems. A special treatment is necessary to clear these problems. A cut cell method on Cartesian grids has been developed to simulate three-dimensional mold filling Cut cells at a cast-mold interface are generated on Cartesian grids. Governing equations were computed using volume and areas of cast at cut cells. In this paper, we propose a new method that can consider the cutting cells which are cut by casting and mold based on the patial cell treatment (PCT). This method provides a better representation of geometry surface and will be used in the computation of velocities that are defined on the cell boundaries in the Cartesian gird system. Various test examples for several casting process were computed and validated. The analysis results of more accurate fluid flow pattern and less momentum loss owing to the stepped boundaries in the Cartesian grid system were confirmed. We can know the momentum energy at the cut cell is conserved by using the cut cell method. By using the cut cell method. performance of computation gets better because of reducing the whole number of meshes.

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유한요소법을 이용한 축대칭 주조의 응고 및 변형공정 해석

  • 구본영;금영탁
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.337-341
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    • 1997
  • The purpare of this research is to develope a FEM program for analyzing solidification processes of axisymmetic casting, considering phase changes and the contact between the metal and mold. Temperture recovery method is employed for considering the phase changes releasing the latent heat. A gap element is employed for modeling the interface between the model and metal in finding deformed shapes. In order to verify the developed program, an axisymmetric aluminum casting processes is simulated. Temperature distribution, phase front position, and shrinkaga and porosity creation are compared with measurement, FIDAP results, and ANSYS results, and good agreements are examined.

Solidification Phenomena of Al-4.5wt.% Cu Alloy under Moderate Pressures (고압하에서의 Al-4.5wt.%Cu합금의 응고현상)

  • Cho, In-Sung;Hong, Chun-Pyo
    • Journal of Korea Foundry Society
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    • v.15 no.2
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    • pp.156-163
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    • 1995
  • Solidification of aluminum alloys under moderate pressures has been investigated. Interfacial heat transfer coefficient at the casting/mold interface varies with time after pouring the molten metal into the die cavity, and therefore plays an important role in determining solidification sequence. The heat transfer coefficients were evaluated by using an inverse problem method, based on the measured temperature distribution. The calculated heat transfer coefficients were used for solidification simulation in the squeeze casting process. The effects of applied pressure and positions of insulation in the mold have also been investigated on solidification microstructures and on the formation of macrosegregation of Al-4.5wt.%Cu alloys.

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